linux-stable.git/drivers/md/md.c, branch linux-3.16.y

md: ensure md devices are freed before module is unloaded.

2017-06-05T20:17:08+00:00

commit 9356863c9409efc79029c01a85d015efae977e69 upstream.

Commit: cbd199837750 ("md: Fix unfortunate interaction with evms")
change mddev_put() so that it would not destroy an md device while
->ctime was non-zero.

Unfortunately, we didn't make sure to clear ->ctime when unloading
the module, so it is possible for an md device to remain after
module unload.  An attempt to open such a device will trigger
an invalid memory reference in:
  get_gendisk -> kobj_lookup -> exact_lock -> get_disk

when tring to access disk->fops, which was in the module that has
been removed.

So ensure we clear ->ctime in md_exit(), and explain how that is useful,
as it isn't immediately obvious when looking at the code.

Fixes: cbd199837750 ("md: Fix unfortunate interaction with evms")
Tested-by: Guoqing Jiang 
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li 
Signed-off-by: Ben Hutchings

md: MD_RECOVERY_NEEDED is set for mddev->recovery

2017-03-16T02:26:31+00:00

commit 82a301cb0ea2df8a5c88213094a01660067c7fb4 upstream.

Fixes: 90f5f7ad4f38("md: Wait for md_check_recovery before attempting device
removal.")

Reviewed-by: NeilBrown 
Signed-off-by: Shaohua Li 
Signed-off-by: Ben Hutchings

md: be careful not lot leak internal curr_resync value into metadata. -- (all)

2017-02-23T03:54:24+00:00

commit 1217e1d1999ed6c9c1e1b1acae0a74ab70464ae2 upstream.

mddev->curr_resync usually records where the current resync is up to,
but during the starting phase it has some "magic" values.

 1 - means that the array is trying to start a resync, but has yielded
     to another array which shares physical devices, and also needs to
     start a resync
 2 - means the array is trying to start resync, but has found another
     array which shares physical devices and has already started resync.

 3 - means that resync has commensed, but it is possible that nothing
     has actually been resynced yet.

It is important that this value not be visible to user-space and
particularly that it doesn't get written to the metadata, as the
resync or recovery checkpoint.  In part, this is because it may be
slightly higher than the correct value, though this is very rare.
In part, because it is not a multiple of 4K, and some devices only
support 4K aligned accesses.

There are two places where this value is propagates into either
->curr_resync_completed or ->recovery_cp or ->recovery_offset.
These currently avoid the propagation of values 1 and 3, but will
allow 3 to leak through.

Change them to only propagate the value if it is > 3.

As this can cause an array to fail, the patch is suitable for -stable.

Reported-by: Viswesh 
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li 
[bwh: Backported to 3.16: there is only one comparison to fix]
Signed-off-by: Ben Hutchings

Revert "md: allow a partially recovered device to be hot-added to an array."

2015-11-16T11:27:17+00:00

commit d01552a76d71f9879af448e9142389ee9be6e95b upstream.

This reverts commit 7eb418851f3278de67126ea0c427641ab4792c57.

This commit is poorly justified, I can find not discusison in email,
and it clearly causes a problem.

If a device which is being recovered fails and is subsequently
re-added to an array, there could easily have been changes to the
array *before* the point where the recovery was up to.  So the
recovery must start again from the beginning.

If a spare is being recovered and fails, then when it is re-added we
really should do a bitmap-based recovery up to the recovery-offset,
and then a full recovery from there.  Before this reversion, we only
did the "full recovery from there" which is not corect.  After this
reversion with will do a full recovery from the start, which is safer
but not ideal.

It will be left to a future patch to arrange the two different styles
of recovery.

Reported-and-tested-by: Nate Dailey 
Signed-off-by: NeilBrown 
Fixes: 7eb418851f32 ("md: allow a partially recovered device to be hot-added to an array.")
Signed-off-by: Luis Henriques

md: flush ->event_work before stopping array.

2015-09-30T12:20:52+00:00

commit ee5d004fd0591536a061451eba2b187092e9127c upstream.

The 'event_work' worker used by dm-raid may still be running
when the array is stopped.  This can result in an oops.

So flush the workqueue on which it is run after detaching
and before destroying the device.

Reported-by: Heinz Mauelshagen 
Signed-off-by: NeilBrown 
Fixes: 9d09e663d550 ("dm: raid456 basic support")
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques

md: use kzalloc() when bitmap is disabled

2015-08-20T14:33:39+00:00

commit b6878d9e03043695dbf3fa1caa6dfc09db225b16 upstream.

In drivers/md/md.c get_bitmap_file() uses kmalloc() for creating a
mdu_bitmap_file_t called "file".

5769         file = kmalloc(sizeof(*file), GFP_NOIO);
5770         if (!file)
5771                 return -ENOMEM;

This structure is copied to user space at the end of the function.

5786         if (err == 0 &&
5787             copy_to_user(arg, file, sizeof(*file)))
5788                 err = -EFAULT

But if bitmap is disabled only the first byte of "file" is initialized
with zero, so it's possible to read some bytes (up to 4095) of kernel
space memory from user space. This is an information leak.

5775         /* bitmap disabled, zero the first byte and copy out */
5776         if (!mddev->bitmap_info.file)
5777                 file->pathname[0] = '\0';

Signed-off-by: Benjamin Randazzo 
Signed-off-by: NeilBrown 
Cc: Moritz Mühlenhoff 
Signed-off-by: Luis Henriques

md: fix a build warning

2015-08-12T08:48:36+00:00

commit 4e023612325a9034a542bfab79f78b1fe5ebb841 upstream.

Warning like this:

drivers/md/md.c: In function "update_array_info":
drivers/md/md.c:6394:26: warning: logical not is only applied
to the left hand side of comparison [-Wlogical-not-parentheses]
      !mddev->persistent  != info->not_persistent||

Fix it as Neil Brown said:
mddev->persistent != !info->not_persistent ||

Signed-off-by: Firo Yang 
Signed-off-by: NeilBrown 
Signed-off-by: Luis Henriques

md: Always set RECOVERY_NEEDED when clearing RECOVERY_FROZEN

2014-11-27T11:21:52+00:00

commit 45eaf45dfa4850df16bc2e8e7903d89021137f40 upstream.

md_check_recovery will skip any recovery and also clear
MD_RECOVERY_NEEDED if MD_RECOVERY_FROZEN is set.
So when we clear _FROZEN, we must set _NEEDED and ensure that
md_check_recovery gets run.
Otherwise we could miss out on something that is needed.

In particular, this can make it impossible to remove a
failed device from an array is the  'recovery-needed' processing
didn't happen.
Suitable for stable kernels since 3.13.

Reported-and-tested-by: Joe Lawrence 
Fixes: 30b8feb730f9b9b3c5de02580897da03f59b6b16
Signed-off-by: NeilBrown 
Signed-off-by: Luis Henriques

md: flush writes before starting a recovery.

2014-07-03T00:44:45+00:00

When we write to a degraded array which has a bitmap, we
make sure the relevant bit in the bitmap remains set when
the write completes (so a 're-add' can quickly rebuilt a
temporarily-missing device).

If, immediately after such a write starts, we incorporate a spare,
commence recovery, and skip over the region where the write is
happening (because the 'needs recovery' flag isn't set yet),
then that write will not get to the new device.

Once the recovery finishes the new device will be trusted, but will
have incorrect data, leading to possible corruption.

We cannot set the 'needs recovery' flag when we start the write as we
do not know easily if the write will be "degraded" or not.  That
depends on details of the particular raid level and particular write
request.

This patch fixes a corruption issue of long standing and so it
suitable for any -stable kernel.  It applied correctly to 3.0 at
least and will minor editing to earlier kernels.

Reported-by: Bill 
Tested-by: Bill 
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/53A518BB.60709@sbcglobal.net
Signed-off-by: NeilBrown

md: make sure GET_ARRAY_INFO ioctl reports correct "clean" status

2014-07-03T00:44:31+00:00

If an array has a bitmap, the when we set the "has bitmap" flag we
incorrectly clear the "is clean" flag.

"is clean" isn't really important when a bitmap is present, but it is
best to get it right anyway.

Reported-by: George Duffield 
Link: http://lkml.kernel.org/CAG__1a4MRV6gJL38XLAurtoSiD3rLBTmWpcS5HYvPpSfPR88UQ@mail.gmail.com
Fixes: 36fa30636fb84b209210299684e1be66d9e58217 (v2.6.14)
Signed-off-by: NeilBrown